Abstract : This Ph.D thesis deals with computing and improving a methodology to numerically model a Mode Stirred Reverberation Chamber (MSRC). This measurement tool allows achieving immunity and susceptibility experiments in the domain of ElectroMagnetic Compatibility (EMC). The aim of this work is to propose a numerical modelling of MSRC taking into account a large number of real characteristics. Thus various criteria were underlined to justify choices achieved to compute time, geometrical and electronic formalisms. Finite Volume in Time Domain (FVTD) technique is mainly used to solve Maxwell's equations. It grants a large geometrical flexibility by allowing designing complex devices, and particularly equipments used in experiments involving MSRC. Losses are preponderant in MSRC studies and are integrated via a specific and realistic filter (based upon MSRC quality factor Q) in a post treatment process from results simulated without losses. However, numerical dissipation from FVTD scheme prevents from easily computing finite volume methods. These works allow evaluating levels of dissipation and to minimize them. A hybrid Finite Difference/Finite Volume in Time Domain (respectively FDTD/FVTD) method is proposed for MSRC studies. Finally various numerical improvements of topical MSRC time domain simulations conclude this thesis.